preparation

Put oven rack in upper third of oven and preheat oven to 425°F. Butter muffin cups. Peel and core apples, then cut into 1/3-inch dice.

Heat 2 tablespoons butter in a 12-inch heavy skillet over moderate heat until foam subsides, then cook apples, brown sugar, and lemon juice, stirring occasionally, until liquid is reduced to a glaze and apples are tender, 5 to 6 minutes.